* [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-08 9:49 ` Xin Long
0 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-08 9:49 UTC (permalink / raw)
To: network dev, linux-sctp
Cc: davem, Marcelo Ricardo Leitner, Vlad Yasevich, daniel
Now sctp uses the transport without holding it in sctp_hash_cmp,
it can cause a use-after-free panic. As after it get transport from
hashtable, another CPU may free it, then the members it accesses
may be unavailable memory.
This patch is to use sctp_transport_hold, in which it checks the
refcnt first, holds it if it's not 0.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
net/sctp/input.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 69444d3..1555fb8 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -796,27 +796,34 @@ struct sctp_hash_cmp_arg {
static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
+ struct sctp_transport *t = (struct sctp_transport *)ptr;
const struct sctp_hash_cmp_arg *x = arg->key;
- const struct sctp_transport *t = ptr;
- struct sctp_association *asoc = t->asoc;
- const struct net *net = x->net;
+ struct sctp_association *asoc;
+ int err = 1;
if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
- return 1;
- if (!net_eq(sock_net(asoc->base.sk), net))
- return 1;
+ return err;
+ if (!sctp_transport_hold(t))
+ return err;
+
+ asoc = t->asoc;
+ if (!net_eq(sock_net(asoc->base.sk), x->net))
+ goto out;
if (x->ep) {
if (x->ep != asoc->ep)
- return 1;
+ goto out;
} else {
if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
- return 1;
+ goto out;
if (!sctp_bind_addr_match(&asoc->base.bind_addr,
x->laddr, sctp_sk(asoc->base.sk)))
- return 1;
+ goto out;
}
- return 0;
+ err = 0;
+out:
+ sctp_transport_put(t);
+ return err;
}
static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
--
2.1.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-08 9:49 ` Xin Long
0 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-08 9:49 UTC (permalink / raw)
To: network dev, linux-sctp
Cc: davem, Marcelo Ricardo Leitner, Vlad Yasevich, daniel
Now sctp uses the transport without holding it in sctp_hash_cmp,
it can cause a use-after-free panic. As after it get transport from
hashtable, another CPU may free it, then the members it accesses
may be unavailable memory.
This patch is to use sctp_transport_hold, in which it checks the
refcnt first, holds it if it's not 0.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
net/sctp/input.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 69444d3..1555fb8 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -796,27 +796,34 @@ struct sctp_hash_cmp_arg {
static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
+ struct sctp_transport *t = (struct sctp_transport *)ptr;
const struct sctp_hash_cmp_arg *x = arg->key;
- const struct sctp_transport *t = ptr;
- struct sctp_association *asoc = t->asoc;
- const struct net *net = x->net;
+ struct sctp_association *asoc;
+ int err = 1;
if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
- return 1;
- if (!net_eq(sock_net(asoc->base.sk), net))
- return 1;
+ return err;
+ if (!sctp_transport_hold(t))
+ return err;
+
+ asoc = t->asoc;
+ if (!net_eq(sock_net(asoc->base.sk), x->net))
+ goto out;
if (x->ep) {
if (x->ep != asoc->ep)
- return 1;
+ goto out;
} else {
if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
- return 1;
+ goto out;
if (!sctp_bind_addr_match(&asoc->base.bind_addr,
x->laddr, sctp_sk(asoc->base.sk)))
- return 1;
+ goto out;
}
- return 0;
+ err = 0;
+out:
+ sctp_transport_put(t);
+ return err;
}
static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
--
2.1.0
^ permalink raw reply related [flat|nested] 14+ messages in thread
* RE: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
2016-09-08 9:49 ` Xin Long
@ 2016-09-08 12:45 ` David Laight
-1 siblings, 0 replies; 14+ messages in thread
From: David Laight @ 2016-09-08 12:45 UTC (permalink / raw)
To: 'Xin Long', network dev, linux-sctp
Cc: davem, Marcelo Ricardo Leitner, Vlad Yasevich, daniel
From: Xin Long
> Sent: 08 September 2016 10:49
> Now sctp uses the transport without holding it in sctp_hash_cmp,
> it can cause a use-after-free panic. As after it get transport from
> hashtable, another CPU may free it, then the members it accesses
> may be unavailable memory.
How old is this bug?
Is it in any release kernels?
David
^ permalink raw reply [flat|nested] 14+ messages in thread
* RE: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-08 12:45 ` David Laight
0 siblings, 0 replies; 14+ messages in thread
From: David Laight @ 2016-09-08 12:45 UTC (permalink / raw)
To: 'Xin Long', network dev, linux-sctp
Cc: davem, Marcelo Ricardo Leitner, Vlad Yasevich, daniel
From: Xin Long
> Sent: 08 September 2016 10:49
> Now sctp uses the transport without holding it in sctp_hash_cmp,
> it can cause a use-after-free panic. As after it get transport from
> hashtable, another CPU may free it, then the members it accesses
> may be unavailable memory.
How old is this bug?
Is it in any release kernels?
David
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
2016-09-08 12:45 ` David Laight
@ 2016-09-08 13:17 ` Xin Long
-1 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-08 13:17 UTC (permalink / raw)
To: David Laight
Cc: network dev, linux-sctp, davem, Marcelo Ricardo Leitner,
Vlad Yasevich, daniel
>> Now sctp uses the transport without holding it in sctp_hash_cmp,
>> it can cause a use-after-free panic. As after it get transport from
>> hashtable, another CPU may free it, then the members it accesses
>> may be unavailable memory.
>
> How old is this bug?
I think since:
$ git describe 33c1529
v4.4-rc7-1158-g33c1529
> Is it in any release kernels?
>
yes
it was found in s390x, we could not reproduce it in x86_64 by now.
Maybe it needs low configuration cpu to reproduce.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-08 13:17 ` Xin Long
0 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-08 13:17 UTC (permalink / raw)
To: David Laight
Cc: network dev, linux-sctp, davem, Marcelo Ricardo Leitner,
Vlad Yasevich, daniel
>> Now sctp uses the transport without holding it in sctp_hash_cmp,
>> it can cause a use-after-free panic. As after it get transport from
>> hashtable, another CPU may free it, then the members it accesses
>> may be unavailable memory.
>
> How old is this bug?
I think since:
$ git describe 33c1529
v4.4-rc7-1158-g33c1529
> Is it in any release kernels?
>
yes
it was found in s390x, we could not reproduce it in x86_64 by now.
Maybe it needs low configuration cpu to reproduce.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
2016-09-08 9:49 ` Xin Long
@ 2016-09-08 19:27 ` Neil Horman
-1 siblings, 0 replies; 14+ messages in thread
From: Neil Horman @ 2016-09-08 19:27 UTC (permalink / raw)
To: Xin Long
Cc: network dev, linux-sctp, davem, Marcelo Ricardo Leitner,
Vlad Yasevich, daniel
On Thu, Sep 08, 2016 at 05:49:04PM +0800, Xin Long wrote:
> Now sctp uses the transport without holding it in sctp_hash_cmp,
> it can cause a use-after-free panic. As after it get transport from
> hashtable, another CPU may free it, then the members it accesses
> may be unavailable memory.
>
> This patch is to use sctp_transport_hold, in which it checks the
> refcnt first, holds it if it's not 0.
>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---
> net/sctp/input.c | 27 +++++++++++++++++----------
> 1 file changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/net/sctp/input.c b/net/sctp/input.c
> index 69444d3..1555fb8 100644
> --- a/net/sctp/input.c
> +++ b/net/sctp/input.c
> @@ -796,27 +796,34 @@ struct sctp_hash_cmp_arg {
> static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
> const void *ptr)
> {
> + struct sctp_transport *t = (struct sctp_transport *)ptr;
> const struct sctp_hash_cmp_arg *x = arg->key;
> - const struct sctp_transport *t = ptr;
> - struct sctp_association *asoc = t->asoc;
> - const struct net *net = x->net;
> + struct sctp_association *asoc;
> + int err = 1;
>
> if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
> - return 1;
> - if (!net_eq(sock_net(asoc->base.sk), net))
> - return 1;
> + return err;
> + if (!sctp_transport_hold(t))
> + return err;
> +
> + asoc = t->asoc;
> + if (!net_eq(sock_net(asoc->base.sk), x->net))
> + goto out;
> if (x->ep) {
> if (x->ep != asoc->ep)
> - return 1;
> + goto out;
> } else {
> if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
> - return 1;
> + goto out;
> if (!sctp_bind_addr_match(&asoc->base.bind_addr,
> x->laddr, sctp_sk(asoc->base.sk)))
> - return 1;
> + goto out;
> }
>
> - return 0;
> + err = 0;
> +out:
> + sctp_transport_put(t);
> + return err;
> }
>
> static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
> --
> 2.1.0
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-sctp" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
What path does this occur in? __sctp_lookup_association takes a hold on the
asoc, and that function is protected by the rcu_read_lock, so I'm not sure how
you get into a situation in which the asoc can be deleted while the lookup is
occuring.
Neil
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-08 19:27 ` Neil Horman
0 siblings, 0 replies; 14+ messages in thread
From: Neil Horman @ 2016-09-08 19:27 UTC (permalink / raw)
To: Xin Long
Cc: network dev, linux-sctp, davem, Marcelo Ricardo Leitner,
Vlad Yasevich, daniel
On Thu, Sep 08, 2016 at 05:49:04PM +0800, Xin Long wrote:
> Now sctp uses the transport without holding it in sctp_hash_cmp,
> it can cause a use-after-free panic. As after it get transport from
> hashtable, another CPU may free it, then the members it accesses
> may be unavailable memory.
>
> This patch is to use sctp_transport_hold, in which it checks the
> refcnt first, holds it if it's not 0.
>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---
> net/sctp/input.c | 27 +++++++++++++++++----------
> 1 file changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/net/sctp/input.c b/net/sctp/input.c
> index 69444d3..1555fb8 100644
> --- a/net/sctp/input.c
> +++ b/net/sctp/input.c
> @@ -796,27 +796,34 @@ struct sctp_hash_cmp_arg {
> static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
> const void *ptr)
> {
> + struct sctp_transport *t = (struct sctp_transport *)ptr;
> const struct sctp_hash_cmp_arg *x = arg->key;
> - const struct sctp_transport *t = ptr;
> - struct sctp_association *asoc = t->asoc;
> - const struct net *net = x->net;
> + struct sctp_association *asoc;
> + int err = 1;
>
> if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
> - return 1;
> - if (!net_eq(sock_net(asoc->base.sk), net))
> - return 1;
> + return err;
> + if (!sctp_transport_hold(t))
> + return err;
> +
> + asoc = t->asoc;
> + if (!net_eq(sock_net(asoc->base.sk), x->net))
> + goto out;
> if (x->ep) {
> if (x->ep != asoc->ep)
> - return 1;
> + goto out;
> } else {
> if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
> - return 1;
> + goto out;
> if (!sctp_bind_addr_match(&asoc->base.bind_addr,
> x->laddr, sctp_sk(asoc->base.sk)))
> - return 1;
> + goto out;
> }
>
> - return 0;
> + err = 0;
> +out:
> + sctp_transport_put(t);
> + return err;
> }
>
> static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
> --
> 2.1.0
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-sctp" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
What path does this occur in? __sctp_lookup_association takes a hold on the
asoc, and that function is protected by the rcu_read_lock, so I'm not sure how
you get into a situation in which the asoc can be deleted while the lookup is
occuring.
Neil
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
2016-09-08 19:27 ` Neil Horman
@ 2016-09-09 7:24 ` Xin Long
-1 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-09 7:24 UTC (permalink / raw)
To: Neil Horman
Cc: network dev, linux-sctp, davem, Marcelo Ricardo Leitner,
Vlad Yasevich, daniel
>>
> What path does this occur in? __sctp_lookup_association takes a hold on the
> asoc, and that function is protected by the rcu_read_lock, so I'm not sure how
> you get into a situation in which the asoc can be deleted while the lookup is
> occuring.
>
yes that function is protected by the rcu_read_lock, it can only
ensure sctp_transport_destroy_rcu will NOT be called. But,
sctp_transport_destroy can be called by sctp_assocation_free.
in which, sctp free and unhash all the transport. when transport's
defcnt become 0, sctp will call sctp_transport_destroy, in which,
asoc can be destroyed because of:
if (transport->asoc)
sctp_association_put(transport->asoc);
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-09 7:24 ` Xin Long
0 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-09 7:24 UTC (permalink / raw)
To: Neil Horman
Cc: network dev, linux-sctp, davem, Marcelo Ricardo Leitner,
Vlad Yasevich, daniel
>>
> What path does this occur in? __sctp_lookup_association takes a hold on the
> asoc, and that function is protected by the rcu_read_lock, so I'm not sure how
> you get into a situation in which the asoc can be deleted while the lookup is
> occuring.
>
yes that function is protected by the rcu_read_lock, it can only
ensure sctp_transport_destroy_rcu will NOT be called. But,
sctp_transport_destroy can be called by sctp_assocation_free.
in which, sctp free and unhash all the transport. when transport's
defcnt become 0, sctp will call sctp_transport_destroy, in which,
asoc can be destroyed because of:
if (transport->asoc)
sctp_association_put(transport->asoc);
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
2016-09-08 9:49 ` Xin Long
@ 2016-09-10 2:17 ` David Miller
-1 siblings, 0 replies; 14+ messages in thread
From: David Miller @ 2016-09-10 2:17 UTC (permalink / raw)
To: lucien.xin; +Cc: netdev, linux-sctp, marcelo.leitner, vyasevich, daniel
From: Xin Long <lucien.xin@gmail.com>
Date: Thu, 8 Sep 2016 17:49:04 +0800
> Now sctp uses the transport without holding it in sctp_hash_cmp,
> it can cause a use-after-free panic. As after it get transport from
> hashtable, another CPU may free it, then the members it accesses
> may be unavailable memory.
>
> This patch is to use sctp_transport_hold, in which it checks the
> refcnt first, holds it if it's not 0.
>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
Please add more detail to the commit message and add a proper
"Fixes: " tag right before your signoff.
Thanks.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-10 2:17 ` David Miller
0 siblings, 0 replies; 14+ messages in thread
From: David Miller @ 2016-09-10 2:17 UTC (permalink / raw)
To: lucien.xin; +Cc: netdev, linux-sctp, marcelo.leitner, vyasevich, daniel
From: Xin Long <lucien.xin@gmail.com>
Date: Thu, 8 Sep 2016 17:49:04 +0800
> Now sctp uses the transport without holding it in sctp_hash_cmp,
> it can cause a use-after-free panic. As after it get transport from
> hashtable, another CPU may free it, then the members it accesses
> may be unavailable memory.
>
> This patch is to use sctp_transport_hold, in which it checks the
> refcnt first, holds it if it's not 0.
>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
Please add more detail to the commit message and add a proper
"Fixes: " tag right before your signoff.
Thanks.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
2016-09-10 2:17 ` David Miller
@ 2016-09-10 15:08 ` Xin Long
-1 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-10 15:08 UTC (permalink / raw)
To: David Miller
Cc: network dev, linux-sctp, Marcelo Ricardo Leitner,
Vladislav Yasevich, daniel
>
> Please add more detail to the commit message and add a proper
> "Fixes: " tag right before your signoff.
OK, will repost v2
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp
@ 2016-09-10 15:08 ` Xin Long
0 siblings, 0 replies; 14+ messages in thread
From: Xin Long @ 2016-09-10 15:08 UTC (permalink / raw)
To: David Miller
Cc: network dev, linux-sctp, Marcelo Ricardo Leitner,
Vladislav Yasevich, daniel
>
> Please add more detail to the commit message and add a proper
> "Fixes: " tag right before your signoff.
OK, will repost v2
^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2016-09-10 15:14 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-09-08 9:49 [PATCH net] sctp: hold the transport before using it in sctp_hash_cmp Xin Long
2016-09-08 9:49 ` Xin Long
2016-09-08 12:45 ` David Laight
2016-09-08 12:45 ` David Laight
2016-09-08 13:17 ` Xin Long
2016-09-08 13:17 ` Xin Long
2016-09-08 19:27 ` Neil Horman
2016-09-08 19:27 ` Neil Horman
2016-09-09 7:24 ` Xin Long
2016-09-09 7:24 ` Xin Long
2016-09-10 2:17 ` David Miller
2016-09-10 2:17 ` David Miller
2016-09-10 15:08 ` Xin Long
2016-09-10 15:08 ` Xin Long
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.